1. Field of the Invention
This invention relates to a tongue assembly for use in a safety apparatus having a belt for restraining an occupant of a vehicle against movement relative to the vehicle. More specifically, this invention relates to a free-running tongue assembly for use in a three-point continuous loop safety belt system.
2. Prior Art
Three-point continuous loop safety belt systems include a safety belt upon which a tongue assembly is slidably mounted. When the safety belt is to be connected to restrain an occupant of a vehicle, the belt is withdrawn from a retractor and the tongue assembly is connected with a buckle. When the tongue assembly is released from the buckle, the belt is wound on the retractor into a stowed position.
In a standard tongue assembly, there is a high level of friction between the tongue assembly and the belt, and the retractor spring is not strong enough to pull the belt through the tongue assembly. As the retractor rewinds the belt, both the belt and the tongue assembly are pulled upwardly by the retractor. If the tongue assembly comes up against the D-ring or retractor before retraction is completed, retraction stops because the retractor cannot pull the belt through the tongue assembly. Some belt webbing is left loose and unretracted. Since both the belt and the tongue assembly are lifted by the retractor, the retractor must have a relatively strong wind-up spring, capable of exerting enough force on the belt to lift the combined weight of the belt and tongue assembly. When the belt is in use, the relatively large force exerted by the retractor wind-up spring results in the belt being pulled across the torso of an occupant of the vehicle with a force which some occupants may find to be objectionably large.
A second type of tongue assembly is known in which there is less friction between the belt and the tongue assembly. However, enough friction remains so that the tongue does not fall freely toward the floor but rather is lifted to the D-ring or retractor. When the tongue assembly contacts the D-ring or retractor, the retractor pulls the belt through the tongue assembly, and excess webbing is stowed onto the retractor. The retractor spring must be strong enough to lift the tongue and overcome the friction between the belt and tongue.
Other systems have been designed with even less friction. U.S. Pat. No. 4,551,889 discloses a self-locking adjust tongue assembly which, when unlatched, has a lock bar depressed from the plane of the base, to permit the adjust tongue to fall freely along the belt when the belt assumes a near vertical position. U.S. Pat. No. 3,941,419 discloses a buckle component which is free to slide down the belt when the belt is in a vertical stored orientation. Co-pending U.S. patent application Ser. No. 280,148 entitled "Tongue Assembly", filed Dec. 5, 1988 by Alexander P. Kotikovsky et al., U.S. Pat. No. 4,878,272 assigned to the assignee of the present application, discloses a tongue assembly through which a belt extends with first and second straight portions having an included angle between them of at least 154.degree., so that the tongue assembly is able to slide on the belt under the influence of gravity. Co-pending U.S. patent application Ser. No. 256,983, filed Oct. 13, 1988 by Alexander P. Kotikovsky entitled "Tongue Assembly" and assigned to the assignee of the present application, discloses a tongue assembly in which there is a minimum amount of friction between the belt and the tongue assembly, so that the two can move easily relative to each other.